Use of combined resonators in widening the continuous tuning band of the emission frequency of gas lasers

An analysis is made of the problem of widening the band of continuous tuning of the emission frequency of a CO₂ laser with an open resonator. Tuning throughout the gain profile is possible by selection of longitudinal modes of the laser resonator. This can be done using a combined resonator with two selection components: a diffraction grating and a diffraction reflecting interferometer with a Troitskii selector. The sharpness factor of a selector needed to select a single longitudinal mode is found. A report is given of experimental attainment of tuning in a 300 MHz band (c/2L=200 MHz) for the P(18) 00⁰1–10⁰0 laser emission line of the CO₂ molecule.